Patent application title: POLYVINYL CHLORIDE FIBER FOR ARTIFICIAL HAIR, MANUFACTURING AND APPARATUS OF THE SAME

Abstract:

The present invention is to provide a polyvinyl chloride (PVC) fiber for
artificial hair. The PVC fiber is manufactured by melt spinning a PVC
resin composition with a nozzle, wherein the nozzle has a nozzle hole
having a diameter D and a land length L, and a nozzle leading portion
having a cone angle, and wherein a ratio of L/D is 1-3, a height of the
nozzle leading portion is at least 4 mm, and the cone angle is
20°-90°. The resulting PVC fiber has an arithmetic mean
roughness of 0.18-0.38 μm and a maximum height of 0.5-3.5 μm along
a longitudinal direction, specified by JIS B 0601.

Claims:

1. A method of manufacturing a polyvinyl chloride (PVC) fiber for
artificial hair, comprising the steps of:melt spinning a PVC resin
composition with a nozzle havinga nozzle hole of a diameter D and a land
length L, and a nozzle leading portion having a cone angle, wherein a
ratio of L/D is 1-3, a height of the nozzle leading portion is at least 4
mm, and the cone angle is 20.degree.-90.degree.; anddischarging the PVC
resin composition with an amount of 65-165 g/h per nozzle.

2. The method as claimed in claim 1, wherein said PVC resin composition
contains 100 parts by mass of a PVC resin, (a) 0.3-3.0 parts by mass of a
higher fatty acid ester lubricant, and (b) 0.3-1.5 parts by mass of a
polyethylene lubricant, with a mixing ratio (a)/(b) of 0.5-4.

3. The method as claimed in claim 1, wherein said PVC resin composition
contains 0.2-5.0 parts by mass of an inorganic thermal stabilizer
selected from a hydrotalcite or zeolite.

4. The method as claimed in claim 2, wherein said PVC resin composition
contains 0.2-5.0 parts by mass of an inorganic thermal stabilizer
selected from a hydrotalcite or zeolite.

5. The method as claimed in any one of claims 1, further comprising the
step of discharging the PVC resin composition with an amount of 80-150
g/h.

6. The method as claimed in any one of claims 2, further comprising the
step of discharging the PVC resin composition with an amount of 80-150
g/h.

7. The method as claimed in any one of claims 3, further comprising the
step of discharging the PVC resin composition with an amount of 80-150
g/h.

Description:

REFERENCE TO RELATED APPLICATIONS

[0001]The present application is a Divisional Application of U.S. patent
application Ser. No. 10/574,412, filed on Mar. 31, 2006 which claims the
benefit of Japanese Patent Application No. 2003-345334 filed on Oct. 3,
2003, and to Japanese PCT Application No. PCT/JP2004/014258 filed on Sep.
29, 2004, the disclosures of which are hereby incorporated by reference
as though set forth fully herein.

TECHNICAL FIELD

[0002]The present invention relates to a polyvinyl chloride (PVC) fiber
for artificial hair having a natural gloss, hue and appearance and
utilized for hair ornament products, such as wigs, hairpieces, braids,
and extension hairs, and relates to a manufacturing and apparatus of the
same.

RELATED ART

[0003]Synthetic resins, such as polyester fiber, acrylics fiber, and
polyvinyl chloride (PVC) fiber, have been utilized for artificial hair.
The PVC fiber especially has strength, elongation percentage,
transparency and stable curling so that it is utilized for artificial
hair fiber for head hair. However, the synthetic resins formed by melt
spinning have a flat surface, a strong gloss and tactile impression of
plastic so that the synthetic resins have appearances far from the
natural hair.

[0004]In order to solve the problem, JP-3,175,222,B discloses that
inorganic particles such as silicon oxide and organic particles such as
cross-linked polystyrene are added to the polyester fiber to form a
specified protrusion on a surface thereof. The polyester fiber disclosed
reduces the gloss and slipping but does not reach to the natural hair
with respect to the gloss, tactile impression and appearance. The art
disclosed in JP-3,175,222,B is adapted to a manufacturing of the
polyvinyl chloride (PVC) fiber. However, since the PVC resin has a high
melting viscosity, the PVC resin composition added with the inorganic
particles such as silicon oxide and the organic particles such as
cross-linked polystyrene causes a thread breakage during melt spinning
and lowers the productivity.

[0005]JP,S62-156308,A discloses that a melt spun polyamide fiber is cool
treated to provide an irregular surface thereon. The polyamide fiber
disclosed in JP,S62-156308,A reduces the gloss and slipping but does not
reach to the natural hair with respect to the gloss, tactile impression
and appearance. The art disclosed in JP,S62-156308,A is adapted to the
manufacturing of the PVC fiber. However, the resultant fiber has a small
irregular surface so that the fiber does not reach to the natural hair
with respect to the gloss, tactile impression and appearance.

[0006]JP,S55-76102,A discloses a filament A, which has an even number of
protrusions radially on an outer surface thereof, a filament B, which has
an odd number of protrusions radially on an outer surface thereof, and a
filament C, which is assembled with two or three circular filaments
juxtaposed to each other and has the same contact length as the radius of
each filament, and that these filaments are mixed together to form a wig
filament. The wig filament does not reach to the natural hair with
respect to the gloss, tactile impression and appearance depending on the
sectional shape of the filament and the mixing ratio.

DISCLOSURE OF THE INVENTION

[0007]The present invention is to provide a polyvinyl chloride (PVC) fiber
for artificial hair having a natural gloss, tactile impression and
appearance with strength and formability, and a method for manufacturing
the same and an apparatus thereof.

[0008]According to a first aspect of the present invention, a polyvinyl
chloride (PVC) fiber for artificial hair has an arithmetic mean roughness
Ra of 0.18-0.38 μm and a maximum height Ry of 0.5-3.5 μm along a
longitudinal direction, specified by JIS B 0601, and the PVC fiber is
manufactured by melt spinning a PVC resin composition with a nozzle. The
nozzle has a nozzle hole having a diameter D and a land length L, and a
nozzle leading portion having a cone angle. A ratio of L/D is 1-3, a
height of the nozzle leading portion is at least 4 mm, and the cone angle
is 20°-90°.

[0009]Preferably, the PVC fiber has a section specified by (L*Mmax)/S
of 4.2-7.0, wherein Mmax(mm) is the maximum line segment,
S(mm2) is a sectional area, and L(mm) is a length of an outer
circumference.

[0010]Preferably, the PVC resin composition contains 100 parts by mass of
a PVC resin, (a) 0.3-3.0 parts by mass of a higher fatty acid ester
lubricant, (b) 0.3-1.5 parts by mass of a polyethylene lubricant, with a
mixing ratio (a)/(b) of 0.5-4.

[0011]Preferably, the PVC resin composition contains 0.2-5.0 parts by mass
of an inorganic thermal stabilizer selected from a hydrotalcite or
zeolite.

[0012]According to a second aspect of the present invention, a method of
manufacturing a polyvinyl chloride (PVC) fiber for artificial hair,
includes the steps of: melt spinning a PVC resin composition with a
nozzle having a nozzle hole having a diameter D and a land length L and a
nozzle leading portion having a cone angle, wherein a ratio of L/D is
1-3, a height of the nozzle leading portion is at least 4 mm, and the
cone angle is 20°-90°; and discharging the PVC resin
composition with an amount of 65-165 g/h per nozzle.

[0013]Preferably, the PVC resin composition contains 100 parts by mass of
a PVC resin, (a) 0.3-3.0 parts by mass of a higher fatty acid ester
lubricant, and (b) 0.3-1.5 parts by mass of a polyethylene lubricant,
with a mixing ratio (a)/(b) of 0.5-4.

[0014]Preferably, the PVC resin composition contains 0.2-5.0 parts by mass
of an inorganic thermal stabilizer selected from a hydrotalcite or
zeolite.

[0015]Preferably, the method further includes the step of discharging the
PVC resin composition with an amount of 80-150 g/h.

[0016]According to a third aspect of the present invention, a melt
spinning apparatus for manufacturing a polyvinyl chloride fiber for
artificial hair, has a nozzle and the nozzle includes: a nozzle hole
having a diameter D and a land length L; and a nozzle leading portion
having a cone angle, wherein a ratio of L/D is 1-3, a height of the
nozzle leading portion is at least 4 mm, and the cone angle is
20°-90°.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a schematic sectional view of a nozzle for manufacturing a
polyvinyl chloride (PVC) fiber for artificial hair of an embodiment of
the present invention by melt spinning a PVC resin composition;

[0018]FIG. 2 is a schematic sectional view of the PVC fiber for artificial
hair of another embodiment of the present invention;

[0019]FIG. 3 is a schematic sectional view of a PVC fiber having a
circular section;

[0020]FIG. 4 is a schematic sectional view of a PVC fiber having a
gear-shaped section;

[0021]FIG. 5 is a schematic sectional view of a PVC fiber having
glasses-shaped section;

[0022]FIG. 6 is a schematic sectional view of a PVC fiber having a
Y-shaped section; and

[0023]FIG. 7 is a schematic sectional view of a PVC fiber having a
five-leaf shaped section.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024]FIG. 1 is a schematic sectional view of an embodiment of a nozzle of
the present invention for manufacturing a polyvinyl chloride (PVC) fiber
for artificial hair by melt spinning a PVC resin composition;

[0025]FIG. 2 is a schematic sectional view of an embodiment of the PVC
fiber for artificial hair of the present invention;

[0026]FIG. 3 is a schematic sectional view of other embodiment of the PVC
fiber for artificial hair of the present invention having a circular
section;

[0027]FIG. 4 is a schematic sectional view of other embodiment of the PVC
fiber for artificial hair of the present invention having a gear-shaped
section;

[0028]FIG. 5 is a schematic sectional view of other embodiment of the PVC
fiber for artificial hair of the present invention having a
glasses-shaped section;

[0029]FIG. 6 is a schematic sectional view of other embodiment of the PVC
fiber for artificial hair of the present invention having a Y-shaped
section; and

[0030]FIG. 7 is a schematic sectional view of other embodiment of the PVC
fiber for artificial hair of the present invention having a five-leaf
shaped section.

[0031]The PVC fiber for artificial hair is manufactured with a nozzle 10
depicted in FIG. 1. The nozzle 10 has a nozzle hole 2 with a diameter of
D and a land length L. A ratio of L/D is 1-3 and a height of a nozzle
leading portion 1 is at least 4 mm. The nozzle leading portion 1 has a
cone angle of 20°-90° at the nozzle hole 2. A unit nozzle
discharges 65-165 g/h. The resulting PVC fiber for artificial hair has an
arithmetic mean roughness Ra of 0.18-0.38 μm and the maximum height Ry
of 0.5-3.5 μm along a longitudinal direction specified in JIS B 0601.

[0033]The arithmetic mean roughness Ra and maximum height Ry are
calculated with a calculating formula specified in JIS B 0601. The
arithmetic mean roughness is given by an Equation 1,

Ra = 1 300 ∫ 0 300 f ( x ) x
Equation 1 ##EQU00001##

[0034]wherein x-axis extends longitudinally to the PVC fiber and is a mean
value of the roughness of the length 300 μm and y-axis intersects to
x-axis and a roughness curve is defined by y=f(x) in unit of μm.

[0035]The maximum height Ry is defined by a difference between a peak and
a valley of the roughness curve extending 300 μm.

[0036]A structure of a tip of the nozzle affects the state of mixing of
the PVC resin. When the nozzle has the tip of L/D less than 1, the PVC
resin is extruded in a turbulent manner so that Ra and Ry become larger
than 0.38 and 3.5, respectively resulting to the frequent thread
breakage. When the nozzle has the tip of L/D greater than 3, the PVC
resin becomes a laminar flow, Ra and Ry become smaller than 0.18 and 0.5,
respectively so that the gloss is intensified and the tactile impression
becomes worse. The tip of L/D less than 1 or greater than 3 is common to
the spinning of polyethylene terephthalate (PET) and polypropylene (PP).
However, since the PVC resin has a high melting viscosity and is
subjected to a high pressure at the nozzle, the PVC fiber is affected by
the tip structure specified by L/D. In the present invention, L/D is set
to 1-3. For manufacturing the conventional PVC fiber with the PVC resin,
L/D is usually 4-10.

[0037]The PVC resin generally has a high resin pressure so that the nozzle
having small L/D can not maintain the strength thereof. Accordingly, it
is necessary to specify the cone angle at the nozzle hole and the height
of the nozzle leading portion. When the cone angle is smaller than
20°, the melting resin is extruded in the laminar manner and Ra
becomes less than 0.18 and Ry becomes less than 0.5 so that the gloss is
intensified and the tactile impression becomes worse. When the cone angle
becomes larger than 90°, the resin pressure to the nozzle becomes
higher and tends to damage the nozzle. The resulting values of Ra and Ry
become high. In order to keep the strength of the nozzle, the height of
the nozzle leading portion is kept at least 4 mm with the cone angle of
20°-90°.

[0038]When the discharge of a unit nozzle is less than 65 g/h, the mixing
of the PVC resin is assisted so that Ra becomes less than 0.18 and Ry
becomes less than 0.5. The resulting fiber has a strong gloss and a poor
tactile impression. When the discharge of each nozzle is more than 165
g/h, the mixing of the PVC resin is not enough so that Ra becomes more
than 0.38 and Ry becomes more than 3.5. The resulting fiber has a poor
melt spinning, poor tactile impression and lower strength. In the present
invention, the discharge of the unit nozzle is 65-165 g/h, preferably
80-150 g/h. As a result, the mixing state of the PVC resin can be
controlled so as to form an irregular surface thereon to control the
gloss and tactile impression.

[0039]The PVC fiber for artificial hair is manufactured by melt spinning
the PVC resin composition with a condition of L/D being 1-3, where D is
the diameter of the nozzle hole 2 and L is the land length of the nozzle
2, the height of the nozzle leading portion being at least 4 mm, the cone
angle of the nozzle hole 2 at the nozzle leading portion 1 being
20°-90°, and the discharge of the unit nozzle being 65-165
g/h. The PVC fiber manufactured has the arithmetic mean roughness Ra of
0.18-0.38 μm and the maximum height Ry of 0.5-3.5 μm along the
longitudinal direction specified in JIS B 0601. The resulting PVC fiber
has strength and formability and is utilized for artificial hair having a
natural gloss, tactile impression and appearance.

[0040]The PVC fiber 20 for artificial hair of the present invention has
(L*Mmax)/S of 4.2-7.0, wherein L(mm) is a length of an outer
circumference 12, Mmax(mm) is the maximum line segment 13
intersecting the gravity center, S(mm2) is a sectional area 11 of
the fiber. These values are determined with the noncontact laser optical
microscopy.

[0041]When the (L*Mmax)/S is 4.2-7.0, the PVC fiber has a suppressed
gloss without losing the strength thereof and the endurance of the
nozzle. When the (L*Mmax)/S is less than 4.2, a diffuse reflection
of light is not enough so that the gloss can not be suppressed enough.
When the (L*Mmax)/S is more than 7.0, the endurance of the nozzle
and the strength of the fiber is reduced and the productivity of the melt
spinning decreases.

[0042]As the length of the outer circumference 12 and the maximum line
segment 13 are large, the sectional area 11 is small, and the
(L*Mmax)/S is large, the irregularity of the section of the fiber
increases so that the gloss is suppressed.

[0043]Preferably, the PVC resin composition of the present invention
contains 100 parts by mass of the PVC resin, (a) 0.3-3.0 parts by mass of
a higher fatty acid ester lubricant and (b) 0.3-1.5 parts by mass of a
polyethylene lubricant with a mixing ratio (a)/(b) of 0.5-4. The
resulting PVC fiber provides a natural gloss, tactile impression and
appearance while keeping strength and formability.

[0044]An individual use of the higher fatty acid ester lubricant and the
polyethylene lubricant decreases greatly a friction between the resin and
the molding apparatus so that an agglomeration of grains is formed on the
surface of the fiber and degrades the tactile impression. With the
combination of the higher fatty acid ester lubricant and the polyethylene
lubricant, although the reason not known, the higher fatty acid lubricant
decreases the friction among the grains of the resin and provides the
fiber surface having the natural gloss, tactile impression and
appearance.

[0045]Preferably, the higher fatty acid ester lubricant (a) of the present
invention is a fatty acid ester of alcohol or multiple alcohol. Other
known lubricants can be utilized within the scope of the present
invention. For example, they are hardened oil, butyl stearate,
monoglycerides stearate, pentaerythritol tetrastearate, stearyl stearate
or a mixture thereof.

[0046]The arithmetic mean roughness Ra and the maximum height Ry decrease
as the amount of the higher fatty acid ester lubricant (a) increases.
Preferably, the amount of the higher fatty acid ester lubricant (a) is
0.3-3 parts by mass with respect to 100 parts by mass of the PVC resin.
When the amount thereof is less than 0.3 parts by mass, the friction
among the grains of the PVC resin does not decrease so that the PVC resin
is not sufficiently mixed and the agglomeration of the grains is formed
on the surface of the fiber and degrades the tactile impression. When the
amount thereof is more than 3 parts by mass, the higher fatty acid ester
lubricant reduces too much the friction between the PVC resin and the
molding apparatus so that the PVC resin is not mixed enough and decreases
the spinnability.

[0047]Preferably, the polyethylene lubricant (b) has an average molecular
weight of 2000-6000 and a density of 0.95-0.98. Other known lubricants
can be utilized within the scope of the present invention.

[0048]The arithmetic mean roughness Ra and the maximum height Ry increase
as the amount of the polyethylene lubricant (b) increases. Preferably,
the amount thereof (b) is 0.3-1.5 parts by mass with respect to 100 parts
by mass of the PVC resin. When the amount of the polyethylene lubricant
(b) is less than 0.3 parts by mass, the PVC resin is mixed excessively so
that the gloss can not be suppressed and the tactile impression becomes
more slippery. When the amount of the polyethylene lubricant (b) is more
than 1.5 parts by mass, the PVC resin is not mixed sufficiently so that
the agglomeration of the grains is formed on the surface of the fiber and
degrades the tactile impression.

[0049]The mixing ratio (a)/(b) of the higher fatty acid ester lubricant
(a) and the polyethylene (b) is preferably 0.5-4. When the mixing ratio
(a)/(b) is less than 0.5, the friction in the spinning apparatus
decreases much more and the PVC resin is not mixed sufficiently so that
the agglomeration of the grains is formed on the surface of the fiber and
degrades the tactile impression. When the mixing ratio (a)/(b) is more
than 4, the higher fatty acid ester lubricant reduces too much the
friction between the PVC resin and the surface of the spinning apparatus,
and the PVC resin is not mixed enough so that the spinnability is
reduced.

[0050]The surface roughness of the PVC fiber of the present invention can
be adjusted with an additive, a control of molding and a post treatment
besides the lubricants.

[0051]Preferably, the PVC resin composition contains 0.2-5.0 parts by mass
of an inorganic thermal stabilizer selected from hydrotalcite or zeolite.
The addition of the inorganic thermal stabilizer to the PVC resin
composition forms the irregularity on the surface of the fiber and
provides an artificial hair with the gloss being suppressed.

[0052]The surface roughness of the PVC fiber of the present invention can
be adjusted with a combination of the known method, such as the additive,
the control of molding and the post treatment, besides the lubricants.

[0053]The control of the surface roughness with the additive is achieved
by controlling the amount of the thermal stabilizer or modifying resin,
or by changing the shape, for example fine powder, of the additive. For
example, a cross-linking polymethyl methacrylate keeps the shape after
the melt spinning so that the arithmetic mean roughness Ra and maximum
height Ry can be adjusted with the control of the mean diameter and
amount of the additive. The addition of the cross-linking polymethyl
methacrylate having a mean diameter of 3 μm changes Ry little and
increases Ra. The addition thereof with a mean diameter of 8 μm
increases Ry without changing Ra.

[0054]The control to adjust the molding condition is to change (1)
temperature of a cylinder of an extruding apparatus or die at the melt
spinning, (2) a number of rotation of a screw, (3) temperature at a
stretching process and a stretching length, (4) temperature and length
for thermal relaxing the stretched fiber. For example, when the
temperature of the cylinder is lowered, the mixing of the PVC resin
becomes worse so that the arithmetic mean roughness Ra and the maximum
height Ry become large. When the PVC fiber is heat treated at a higher
temperature, the surface shape thereof is relaxed so that the arithmetic
mean roughness Ra and the maximum height Ry become small.

[0055]A vibration of an order of micrometer is applied, directly or
indirectly through air or coolant, to a nozzle or the fiber injected from
the nozzle at the melt spinning so as to form the irregularity of the
natural hair to the fiber.

[0056]The surface of the fiber can be controlled with a post treatment
such as a chemical treatment with a chemical agent, or a physical
treatment with a plasma discharge or gear forming to control the
arithmetic mean roughness Ra.

[0058]A mean degree of polymerization of the PVC resin is preferably
600-1600. The mean degree of polymerization of less than 600 lowers a
melting viscosity and produces the fiber having a high thermal
contraction. The mean degree of polymerization of more than 1600
increases the melting viscosity and increases the molding temperature
resulting to a color change to the fiber.

[0060]The PVC fiber for artificial hair of the present invention has a
diameter of 20-100 denier, or preferably 50-80 denier. The fiber with the
diameter of 20-100 denier appears like natural human hair and the fiber
of 50-80 denier has an improved tactile impression and appearance.

[0061]The PVC fiber for artificial hair of the present invention may have
any sectional shapes shown in FIGS. 3-7.

[0062]The PVC fiber is melt spun with the nozzle 10, as shown in FIG. 1,
of the ratio L/D of 1-3 for the nozzle hole diameter D and land length L,
having the height of the nozzle leading portion of at least 4 mm and the
cone angle of 20-90° at the nozzle leading portion 1, with the
discharge amount of 65-165 g/h. The resulting PVC fiber provides the
artificial hair having the natural gloss, tactile impression and
appearance while maintaining strength and formability.

[0063]The PVC resin composition preferably contains 100 parts by mass of
the PVC resin, (a) 0.3-3.0 parts by mass of the higher fatty acid ester
lubricant and (b) 0.3-1.5 parts by mass of the polyethylene lubricant
with the ratio (a)/(b) of 0.5-4. The resulting PVC fiber provides the
artificial hair having the natural gloss, tactile impression and
appearance while maintaining strength and formability.

[0064]The PVC resin composition preferably contains 0.2-5.0 parts by mass
of the inorganic thermal stabilizer selected from the hydrotalcite or
zeolite. The resulting PVC fiber provides the artificial hair having the
suppressed gloss with ease of formation of the irregularity on the
surface thereof.

[0065]In the present invention, the amount of the discharge is selected to
80-150 g/h to achieve the PVC fiber having the natural gloss, tactile
impression and appearance while maintaining strength and formability.

[0066]The PVC resin composition is in the form of the powder compound
prepared by Henschel mixer or ribbon blender, or a pellet compound melt
together. A single extruder, twin extruder or conical twin extruder is
utilized for manufacturing the PVC fiber at a temperature of
170-190° C. Finally, the PVC fiber is processed through the
stretching process and thermal relaxing process.

[0067]The shape of the section of the PVC fiber, related to
(L*Mmax)/S, is adjusted by changing the nozzle shape at the melt
spinning. In the present invention, the shape of the section of the PVC
fiber is not specifically limited and may have the sections shown in
FIGS. 3-7. The value of (L*Mmax)/S is 4.0 for the circular shape and
becomes larger as the shape becomes complicated.

[0069]The PVC fiber of the present invention has the diameter of 20-100
denier, or preferably 50-80 denier. The fiber with the diameter of 20-100
denier appears like natural human hair and the fiber of 50-80 denier has
the improved tactile impression and appearance.

[0070]The PVC fiber is melt spun with the nozzle 10, as shown in FIG. 1,
of the ratio L/D of 1-3 for the nozzle hole diameter D and land length L,
having the height of the nozzle leading portion of at least 4 mm and the
cone angle of 20°-90° at the nozzle leading portion 1. The
resulting PVC fiber provides artificial hair having the natural gloss,
tactile impression and appearance while maintaining strength and
formability.

EXAMPLE

Example 1

[0071]A PVC resin composition contains 100 parts by mass of a PVC resin
(TAIYO-ENBI, TH-1000), 3 parts by mass of a hydrotalcite (KYOWA-KAGAKU,
ALCAMIZER-1), 0.6 parts by mass of a 12 zinc hydroxystearate
(NISSAN-KAGAKU, NF-12Zn), 0.4 parts by mass of a 12 calcium
hydroxystearate (NISSAN-KAGAKU, NF-12Ca), and a lubricant including 4.0
parts by mass of a higher fatty acid ester lubricant (RIKEN-BITAMIN,
EW-100) and 0.2 parts by mass of a polyethylene wax (MITUI-SEKIYU-KAGAKU,
Hiwax400P) with a mixing ratio of 20. A nozzle for melt spinning has a
section area of 0.06 mm2, L/D of 3, where D is the diameter of the
nozzle hole and L is the land length, the height of nozzle leading
portion of 5 mm, and the cone angle of 50°. The PVC resin
composition is melt spun with 120 nozzles, each having a circular
section, at a temperature of 175° C. with a discharge amount of
125 g/h. The melt spun PVC fiber has the circular section shown in FIG. 3
and a mean fineness of 180 denier. The PVC fiber is stretched to 300% at
a temperature of 105° C. in air. The PVC fiber is then heat
treated at a temperature of 110° C. in air until the length
thereof contracts to 75% of the length prior to the heat treatment to
achieve the PVC fiber of the mean fineness of 60 denier.

Example 2

[0072]Comparing to Example 1, a mixing ratio of the lubricant is changed
to 1.7 and the lubricant contains 1.0 parts by mass of the fatty ester
lubricant (RIKEN-BITAMIN, EW-100) and 0.6 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P).

Example 3

[0073]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 0.1 and the
lubricant contains 0.2 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 1.6 parts by mass of the
polyethylene wax (MITSUI-SEKIYU-KAGAKU, Hiwax 400P). The gear-shaped die
of the nozzle hole, as shown in FIG. 4, having the (L*Mmax)/S=7.4 is
utilized for producing the PVC fiber having a mean fineness of 180
denier.

Example 4

[0074]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 1.7 and the
lubricant contains 1.0 part by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 0.6 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The gear shaped die
of the nozzle hole, as shown in FIG. 4, having the (L*Mmax)/S=7.4 is
utilized for producing the PVC fiber having a mean fineness of 180
denier.

Example 5

[0075]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 0.3 and the
lubricant contains 0.4 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 1.2 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The glasses shaped
die of the nozzle hole, as shown in FIG. 5, having the
(L*Mmax)/S=5.6 is utilized for producing the PVC fiber having a mean
fineness of 180 denier.

Example 6

[0076]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 1.7 and the
lubricant contains 1.0 part by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 0.6 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The glasses shaped
die of the nozzle hole, as shown in FIG. 5, having the
(L*Mmax)/S=5.6 is utilized for producing the PVC fiber having a mean
fineness of 180 denier.

Example 7

[0077]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 0.5 and the
lubricant contains 0.2 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 0.4 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The Y-shaped type die
of the nozzle hole, as shown in FIG. 6, having the (L*Mmax)/S=5.6 is
utilized for producing the PVC fiber having a mean fineness of 180
denier.

Example 8

[0078]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 3.5 and the
lubricant contains 0.7 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 0.2 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The five-leaf shaped
die of the nozzle hole, as shown in FIG. 7, having the
(L*Mmax)/S=5.6 is utilized for producing the PVC fiber having a mean
fineness of 180 denier.

Comparative Example 1

[0079]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 1.7 and the
lubricant contains 1.7 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 1.4 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The glasses-shaped
die of the nozzle hole, as shown in FIG. 5, having the
(L*Mmax)/S=5.6 is utilized for producing the PVC fiber having a mean
fineness of 180 denier.

Comparative Example 2

[0080]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 0.5 and the
lubricant contains 0.6 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 1.2 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The Y-shaped type die
of the nozzle hole, as shown in FIG. 6, having the (L*Mmax)/S=5.6 is
utilized for producing the PVC fiber having a mean fineness of 180
denier.

Comparative Example 3

[0081]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 1.0 and the
lubricant contains 0.4 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 0.4 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The Y-shaped type die
of the nozzle hole, as shown in FIG. 6, having the (L*Mmax)/S=5.6 is
utilized for producing the PVC fiber having a mean fineness of 180
denier.

Comparative Example 4

[0082]Comparing to Example 1, the mixing ratio of the lubricant and the
shape of the nozzle hole are changed. The mixing ratio is 0.6 and the
lubricant contains 0.8 parts by mass of the higher fatty acid ester
lubricant (RIKEN-BITAMIN, EW-100) and 1.4 parts by mass of the
polyethylene wax (MITUI-SEKIYU-KAGAKU, Hiwax 400P). The glasses-shaped
die of the nozzle hole, as shown in FIG. 5, having the
(L*Mmax)/S=5.6 is utilized for producing the PVC fiber having a mean
fineness of 180 denier.

[0085]The noncontact laser microscope (VK-8500 by KEYENCE KABUSHIKI
KAISHA) is utilized with an objective 50 times and a measuring distance
of 0.02 μm. The measurements are made on 10 points on each of three
samples with the distance of 300 μm along the longitudinal direction
so as to measure the arithmetic mean roughness Ra and the maximum height
Ry specified in JIS B 0601.

[0086](2) Section of Fiber

[0087]The noncontact laser microscope (VK-8500 by KEYENCE KABUSHIKI
KAISHA) is utilized with the objective 50 times and the measuring
distance of 0.1 μm. The maximum line segment Mmax(μm) passing
through the gravity center and the length of the outer circumference
L(μm) and the sectional area(μm2) are measured to evaluate
(L*Mmax)/S.

[0088](3) Gloss

[0089]The gloss is evaluated by a visual examination to a bundle of 24,000
fibers under sunlight and fluorescent light. The symbols ◯,
Δ, × each represent that the surface of the fiber is flat and
has a little gloss, that the surface of the fiber has a large
irregularity and a little gloss, or the surface is flat and has a little
gloss, and that the surface thereof has a large irregularity and no
gloss, or the surface thereof is flat and has a strong gloss,
respectively.

[0090](4) Tactile Impression

[0091]The tactile impression is obtained from a feeling of a touch when
the fibers bundled with 24,000 fibers are rubbed with hand. The symbols
◯, Δ, × each represent that the tactile
impression is a smooth touch, a rasping or a little slippery touch, and
the rasping or a strong slippery, respectively.

[0092](5) Strength

[0093]The strength of the fiber is measured with a Autograph AGS-5D of
SHIMAZU-SEISAKUSHO. The symbols ◯, Δ and × each
represent that the fiber strength is at least 1.4 g/denier, 1.2-1.4
g/denier and less than 1.2 g/denier, respectively.

[0094](6) Spinnability

[0095]The spinnability is determined from a number of thread breakage
during melt spinning the PVC resin composition with 120 dies for a period
of 30 min with 3 repetitions. The symbols ◯, Δ and
× each represent that the thread breakage is zero, once, and twice
or more, respectively.

[0097]As clearly seen from TABLE 1, Examples 1-7 show that the PVC fibers
have the gloss, tactile impression, strength and spinnability of at least
Δ and are adapted for the product. The PVC fibers of Examples 5-8
have a level of ◯ for many evaluation items. Contrary to
this, Comparative Examples 1-3 show that the gloss of the fiber surface
is not suppressed enough. Comparative Example 4 shows a poor spinnability
and tactile impression.

INDUSTRIAL APPLICABILITY

[0098]A PVC fiber for artificial hair of the present invention has a
natural gloss, tactile impression and appearance while maintaining
strength and formability so that the PVC fiber is adapted for
manufacturing of hair ornament products, such as wigs, hair pieces,
braids, and extensions.